Usually, a wireless cellular network refers to a network providing a communication service to mobile terminal devices such as a mobile phone, etc., where the wireless cellular network consists of networks with multiple elements, including each element in a Radio Access Network (RAN) and a Core Network (CN). The RAN includes elements such as a base station, a base station controller, a wireless network controller, etc. A mobile terminal device receives and processes a downlink wireless signal from the wireless cellular network and sends an uplink wireless signal so that communications with a network is realized.
Communications between the wireless cellular network and mobile terminal devices can be classified into two types of service: a Circuit Switching (CS) service and a Packet Switching (PS) service. The CS service includes CS domain voice, message, etc. The PS service includes a service with data transmitted and received in a packet form such as a multimedia message, the Voice over Internet Protocol (VoIP), the HyperText Transfer Protocol (HTTP), the File Transfer Protocol (FTP), etc. For example, for a mobile terminal running an intelligent operating system such as android, iOS, etc., if an application such as QQ, WeChat, Fetion, etc. is run, the mobile terminal logs into a server of the corresponding service provider through a PS domain, send a heartbeat packet periodically, and collect a new message, which is sent by a network, from the server. The network can page through the PS domain, where the network pages the mobile terminal and initiates a data connection in the PS domain so as to acquire data.
Currently, there are multiple parallel radio access technologies existing for the RAN, where the multiple radio access technologies includes 2G, 3G and 4G, that is, from the second generation to the fourth generation. The 2G communication system includes the Global System for Mobile communication (GSM), IS95. The 3G communication system includes the Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), the Wideband Code Division Multiple Access (WCDMA) and the Code Division Multiple Access 2000 (CDMA 2000). The 4G communication system includes Long Term Evolution Advanced (LTE-A), which is an enhancement of the Long Term Evolution (LTE). Although, based on the standard division, the LTE is not categorized into the 4G technology but categorized into the advanced 3G technology, but, in general speaking, the LTE is well known as a 4G technology. Currently, the 5G technology is in a stage of definition required. Based on the recent research, the 5G technology may use even higher frequencies, for example, a bandwidth around 5 GHz.
The GSM and the WCDMA have been developed for a long time, thus the two cellular communication networks have a broader network coverage, such as in-building coverage, underground space, elevator shaft, metro (subway), and a mobile phone generally can find signals of the two cellular communication networks. However, parallel radio access technologies become more and more. Due to constraint of various factors, it is difficult to realize covering multiple cellular networks simultaneously at one location. For example, there is no enough space or no permission for setting up more base stations, antennas or repeaters. Therefore, to a certain degree, a new network will compete with an old network for network coverage resources. However, the 5G network uses even higher frequencies, which will further drop the network coverage.
Using a repeater is one of the important technical approaches for solving a network coverage problem. The repeater includes an amplifying uplink and an amplifying downlink, which consist of components or modules such as an antenna, a Radio Frequency (RF) duplexer, a low noise amplifier, a frequency mixer, a voltage variable attenuator, a filter, a power amplifier, etc. A downlink signal sent from a base station is received by the repeater through a forward-facing antenna (a donor antenna), and then the downlink signal is amplified by the low noise amplifier so as to suppress a signal noise in the downlink signal and improve the Signal to Noise Ratio (SNR). Next, the downlink signal is converted down into an intermediate-frequency signal, and then, the intermediate-frequency signal is filtered and amplified. Next, the intermediate-frequency signal is converted up into a RF signal, and then the RF signal is amplified by the power amplifier and sent to a mobile platform through a back-facing antenna (a repeat antenna). Simultaneously, an uplink signal from the mobile platform is received through the back-facing antenna and the uplink signal is processed by the amplifying uplink along a reverse path, where the uplink signal goes through the low noise amplifier, a down converter, the filter, a intermediate frequency amplifier, an up converter, a power amplifier and then is sent to the base station. Therefore, two-way communications between the base station and the mobile terminal can be realized. Connection between the repeater and the base station may adopt an optical fiber approach or a wireless approach.
Regarding to coverage of scenarios in home-use, basement, ground floor commercial, etc., the conventional repeater has disadvantages including complicated in installation or set up, and high in cost. Therefore, a mini-repeater like product is developed. FIG. 1 schematically illustrates a diagram for use scenario of a mini-size signal strengthen device, or called “a mini-size signal amplifier” or “a micro-power repeater”. Referring to FIG. 1, an outdoor return antenna, such as a plate antenna or a whip antenna, receives a signal from a donor base station and transmits the signal to an indoor micro-power repeater through a RF cable. The micro-power repeater usually includes a printed antenna that is adapted to send an amplified signal. Further, the micro-power repeater receives an uplink signal from an indoor mobile terminal and transmits the uplink signal to the outdoor return antenna through the RF cable, where the outdoor return antenna sends the uplink signal to the donor base station. The micro-power repeater adopts an approach of wireless return, which can enhance signal strength for the 2G/3G/4G system or a part of Radio Access Technologies (RATs) of the 2G/3G/4G system.
Compared to a conventional micro-power repeater, a current micro-power repeater is competitive in cost and volume. However, there is no efficient way for an operator to control the current micro-power repeater, especially, to control each individual current micro-power repeater. Accordingly, it is difficult to add more functionality to a micro-power repeater and improve performance of the micro-power repeater if the cellular wireless network cannot effectively control the micro-power repeater.